Laryngoscopes have been in use for a very long period of time to enable a view to be obtained of the larynx, and to lift tissue adjacent to the epiglottis, or to lift the epiglottis directly, to enable an endotracheal tube to be inserted into a patient's trachea. The first laryngoscopes were direct laryngoscopes, enabling a user to obtain a direct line of sight to the patient's trachea, and direct laryngoscopes are typically straight, curved or angled. Indirect laryngoscopes include a viewing device to enable an indirect view of the trachea to be provided to a user. Early indirect laryngoscopes used a prism, lenses or a series of reflecting mirrors. Later, fibreoptics devices were employed and then video cameras were mounted on the laryngoscope blade (the part which extends into a patient's oral cavity in use) once they became sufficiently small and cost-effective.
Within this specification and the appended claims, by a video laryngoscope, we refer to laryngoscopes including a video camera for obtaining a view before or during the intubation process. Video laryngoscopes may include a video camera as part of the blade. Alternatively, they may include a fibreoptic arrangement which conducts light from a suitable viewing position to a video camera location on the blade or in another part of the laryngoscope, such as the handle, or conceivably remotely from the laryngoscope. By a video display region we refer to a surface area on which video images are shown, excluding boundaries, supports etc.
Video laryngoscopes are known which output video signals to a remote display through a wired or wireless video output interface. The present invention relates to those which include a display for displaying video images obtained from the video camera. The display may be permanently mounted to the laryngoscope, or demountable.
Video laryngoscopes typically have both a handle and a blade, which may be separable or integral to each other. The handle may be at any of a range of angles to the blade, such as around 90°, or generally coaxial with the blade. Blades can be curved, straight and include one of more bends, which may be defined or arise from the smooth changes in curvature. In each case, the term distal is used within this specification and the appended claims to refer to the end of the device which extends furthest towards the larynx in use—typically the end of the blade, and the term proximal is used within this specification and the appended claims to refer to the opposite end of the device, typically an end of the handle opposite the blade.
It is known to provide a video display region which is coplanar with the centre line of video laryngoscopes which have generally bilateral symmetry and located at the most proximal end of the laryngoscope handle. For example, this arrangement is known from the products marketed as Pentax AWS-100 and Coopdech C-Scope (Daiken Medical). A disadvantage of these arrangements is that the relatively high mass of the video screen and supporting electronics can provide a relatively large and bulky device in which the centre of gravity is out of the hand and which is harder to manoeuvre than traditional laryngoscopes.
It is also known to provide a video display region which is entirely laterally offset from the handle of a video laryngoscope, and located at the most proximal end of the laryngoscope handle. This is known from the McGrath Series 5 laryngoscope (McGrath is a trade mark of Aircraft Medical Limited). This works well with the laterally offset blade of the laryngoscope but does increase the overall size of the device.
It is known from U.S. Pat. No. 5,827,178 (Berall) to provide a screen located distally on the handle of a video laryngoscope, very close to the blade. However, this design is impractical as it prevents a user from forming a good grip around the blade. The grip is obscured by the screen.